Traditionally, blind persons communicate, other than orally, by the use of braille and for this purpose there has been developed a machine known as "Perkins Brailler" having nine keys which enables a blind person to quickly and effectively print braille. This machine and other similar machines have solved many communication problems. However braille print cannot be understood by most persons in the community and thus opportunities, particularly employment opportunities, for blind persons are severely limited.
Braille is a shorthand language with many contractions, and wordsigns designated by a single braille code and others designated by two codes. The word `knowledge` is an example, this word is represented in braille by a `space` followed by the letter `K` with a following `space`. As well as the many contractions and wordsigns there are seventy-nine abbreviations. Many of these abbreviations are extendable to other words. The abbreviation for `ABOVE` (braille ABV) can be extended to `ABOVEBOARD`. Printed braille is difficult to understand since braille codes are used for more than one purpose. The second dot set in a braille cell is an example. This can be the contraction `EA`; the comma; the decimal point or the fraction denominator of one and there are of course many other similar cases.
While it is possible at present to provide printing apparatus which a blind person can utilize to provide conventional written English, the presently available apparatus such as typewriters and other electronic printing means have the disadvantage that a blind operator cannot readily check the work in progress. Thus if a blind person is interrupted during use of such a machine, that person may not be able to remember exactly what has already been printed. Additionally, many blind persons are familiar with the operation of the "Perkins Brailler" and indeed own such a machine and it is desirable that such persons be able to communicate by conventional printed language using existing skills associated and developed for the operation of a brailler printing machine.